Firefox Web Dev Plugins I Use

I use Firefox as a regular web dev tool. The following list of plugins I've found helpful in design and coding.

You can find these plugins at Firefox Add-ons

• Web Developer - Adds a menu and a toolbar with various web developer tools. Very powerful.
  
• Firebug - Equally as powerful, with firebug you can edit, debug, and monitor CSS, HTML, and JavaScript live
• MeasureIt - Take the guessing work out of coding widths with this on screen ruler.
  
• ColorZilla - Get that RGB or Hex numbers you need with this screen color picker.
• Palette Grabberr - Creates a color palette for Photoshop, Paint Shop Pro, GIMP, Flash, Fireworks, Paint.NET, or OS X based on the current page. (I don't have much experience with this add-on but it seems great)
• Clear Cache Button - fast way to clear cache in Firefox
  
• Cooliris - works with Google images and Flickr and makes looking for photos a snap
  
• Session Manager - Can use this to save sessions of tabs per client
• ScreenGrab - Copy or save the whole page or just what is visible or just what you choice and in more than one file format. Easy to use and quickly accessible.
  
• Fireshot - (PC only) Screen shot taker and control of file created
  

I'm new to these three possibly very helpful Firefox plugins for web development. These three relate to easily seeing the code structure with a right click on the page. Very useful in seeing what's under the hood.

• Aardvark - Utility for selecting elements and doing various actions on them. It can be used for web development but has other applications.
  
• X-Ray - See the tags on a page without viewing the source code.
• Professor X - See inside a page's head without viewing the sourcecode...

Search of other plugins on Firefox Add-ons in the Web Development section.

(Please comment and/or suggest your own preferences)